| Summary: | <p>Abstract</p> <p>Background</p> <p>The neotropical butterfly <it>Heliconius heurippa </it>has a hybrid colour pattern, which also contributes to reproductive isolation, making it a likely example of hybrid speciation. Here we used phylogenetic and coalescent-based analyses of multilocus sequence data to investigate the origin of <it>H. heurippa</it>.</p> <p>Results</p> <p>We sequenced a mitochondrial region (CoI and CoII), a sex-linked locus (<it>Tpi</it>) and two autosomal loci (<it>w </it>and <it>sd</it>) from <it>H. heurippa </it>and the putative parental species, <it>H. cydno </it>and <it>H. melpomene</it>. These were analysed in combination with data from two previously sequenced autosomal loci, <it>Dll </it>and <it>Inv</it>. <it>H. heurippa </it>was monophyletic at mtDNA and <it>Tpi</it>, but showed a shared distribution of alleles derived from both parental lineages at all four autosomal loci. Estimates of genetic differentiation showed that <it>H. heurippa </it>is closer to <it>H. cydno </it>at mtDNA and three autosomal loci, intermediate at <it>Tpi</it>, and closer to <it>H. melpomene </it>at <it>Dll</it>. Using coalescent simulations with the Isolation-Migration model (IM), we attempted to establish the incidence of gene flow in the origin of <it>H. heurippa</it>. This analysis suggested that ongoing introgression is frequent between all three species and variable in extent between loci.</p> <p>Conclusion</p> <p>Introgression, which is a necessary precursor of hybrid speciation, seems to have also blurred the coalescent history of these species. The origin of <it>Heliconius heurippa</it> may have been restricted to introgression of few colour pattern genes from <it>H. melpomene</it> into the <it>H. cydno</it> genome, with little evidence of genomic mosaicism.</p>
|
|---|
